JP5072226B2 - Pneumatic radial tire for motorcycles - Google Patents

Description

  The present invention relates to a pneumatic radial tire for a motorcycle (hereinafter, also simply referred to as “tire”) used for a high-performance motorcycle generally called a super sports type that is driven at high-speed cornering. The present invention relates to a low-flat pneumatic radial tire for a high-performance motorcycle that maintains various performance such as stability and straight-running stability and improves steering stability performance at high-speed cornering.

  Conventionally, on a pneumatic radial tire for a motorcycle, a belt-like body in which one or a plurality of parallel cords are embedded in a covering rubber is spirally wound in the tire rotation axis direction at an angle toward the tire circumferential direction. A so-called spiral belt layer that is rotated is applied to improve high-speed durability, straight running stability, uniformity performance, acceleration performance, and the like of the tire.

As a technique related to the improvement of a steel cord as a reinforcing material in such a spiral belt layer, for example, Patent Document 1 discloses that a tensile elongation of a belt cord made of a spirally wound steel cord is defined in a predetermined manner, so There is disclosed a radial tire for a motorcycle that does not significantly reduce the straightness and turning performance in the vehicle and that maintains the handling property and improves the wear resistance. Patent Document 2 discloses a motorcycle radial tire defined by a load-elongation curve of a band cord constituting a spirally wound belt-like ply.
JP-A-4-362402 (Claims etc.) JP 2001-130218 A (Claims etc.)

  However, when a spiral belt layer is applied to a pneumatic radial tire for a motorcycle, the above-mentioned various tire performances can be improved, but the reaction when changing the direction of the vehicle becomes dull and the lightness is lost. There was a problem. Therefore, there has been a demand for a tire improvement technique that can ensure the turning maneuverability (cornering performance) while improving the high-speed durability, straight running stability, uniformity performance, acceleration performance, and the like.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a pneumatic radial tire for a motorcycle with improved turning maneuvering performance (cornering performance) without impairing various tire performances such as straight running performance, high speed performance, riding comfort, and uniformity. It is in.

  As a result of earnestly examining the mechanism in which the various tire performances are not compatible when the spiral belt layer is applied, the present inventor can improve the cornering performance at the limit by providing a spiral belt layer to increase the rigidity. As a result, it was found that the familiarity with the road surface worsened and the ground contact reactivity of the tire deteriorated, and as a result, the lightness was lost. In other words, in this case, flexibility is required in order to improve contact with the road surface in the initial stage, but it is considered that high rigidity is required when further input is applied, such as during cornering.

  As a result of further intensive studies from this point of view, the present inventor has found that in order to solve the above problem, the tire is a spiral belt layer made of a steel cord having predetermined physical characteristics, that is, the rubber is flexible in a low load range. Spiral that can improve the fit and robustness of the product by exhibiting various characteristics, and increase the strength and rigidity of the product by exhibiting the characteristics of steel at high loads It has been found that it is effective to apply a belt layer, and the present invention has been completed.

That is, a pneumatic radial tire for a motorcycle according to the present invention includes a tread portion, a pair of sidewall portions disposed radially inward from both edges of the tread portion, and a tire radial direction of the sidewall portion. At least one layer of carcass comprising a bead portion continuous on the inside, each portion being reinforced between bead cores embedded in the bead portion, and a cord forming 60 to 90 ° with respect to the tire equatorial plane covered with rubber A pneumatic radial tire for a motorcycle, comprising a carcass layer made of ply and at least one spiral belt layer spirally formed on the outer side in the tire radial direction of the carcass layer substantially in parallel with the tire equatorial plane. In
The spiral belt layer is composed of a rubber-steel cord composite in which a steel cord composed of a plurality of steel linear bodies is embedded in rubber;
The steel wire is a steel filament, a steel strand formed by twisting a plurality of steel filaments, or a combination thereof,
The steel cord is formed by bundling a plurality of the steel wire bodies spirally formed at substantially the same pitch without being twisted at substantially the same phase,
In the strain-load characteristics when rubber is attached to the circumscribed circle of the steel cord, when the steel section cross-sectional area of the steel cord is S (mm ² ), the additional load W is 1500 × S (N). The amount of elongation when changing to 1600 × S (N) is 0.070% or less, and the additional load W ₁ (N) at the time of 0.35% elongation and the additional load W at the time of 0.45% elongation. ₂ (N) is the following formula,
W ₂ −W ₁ <35 · S
It is characterized by satisfying.

In the present invention, it is preferable that circumscribed circles of the shaping spiral of any one of the steel wire bodies and at least one other steel wire body overlap each other, and the plurality of steel wire bodies It is also preferred that the structure and the amount of molding are all the same. In particular, when the circumscribed circle diameter of the molding spiral of the steel linear body is D and the outer diameter of the steel linear body is d, the following formula:
D> 2.5d
It is preferable to satisfy

The pneumatic radial tire for a motorcycle according to the present invention includes a tread portion, a pair of sidewall portions disposed radially inward from both edges of the tread portion, and a tire radial direction of the sidewall portion. At least one layer of carcass comprising a bead portion continuous on the inside, each portion being reinforced between bead cores embedded in the bead portion, and a cord forming 60 to 90 ° with respect to the tire equatorial plane covered with rubber A pneumatic radial tire for a motorcycle, comprising a carcass layer made of ply and at least one spiral belt layer spirally formed on the outer side in the tire radial direction of the carcass layer substantially in parallel with the tire equatorial plane. In
The spiral belt layer is composed of a rubber-steel cord composite in which a steel cord composed of a plurality of steel linear bodies is embedded in rubber ;
The steel wire is a steel filament, a steel strand formed by twisting a plurality of steel filaments, or a combination thereof,
In the circumscribed circle in the cross section orthogonal to the longitudinal direction of the steel cord, the steel cord is formed by twisting 2 to 5 of the steel wire bodies by excessively shaping them and twisting them together. The central angle with respect to the arc between the rods is 180 ° or more,
In the strain-load characteristics when rubber is attached to the circumscribed circle of the steel cord, when the steel section cross-sectional area of the steel cord is S (mm ² ), the additional load W is 1500 × S (N). The amount of elongation when changing to 1600 × S (N) is 0.070% or less, and the additional load W ₁ (N) at the time of 0.35% elongation and the additional load W at the time of 0.45% elongation. ₂ (N) is the following formula,
W ₂ −W ₁ <35 · S
It is characterized by satisfying.
Also in this case, more preferably, when the circumscribed circle diameter of the steel cord is D and the outer diameter of the steel linear body constituting the steel cord is d, the following formula:
D> 2.5d
Satisfied.

In the present invention, preferably, the additional load W is changed from 1500 × S (N) to 1600 × S (N) in the strain-load characteristics in a state where rubber is adhered to the circumscribed circle of the steel cord. In addition, in the strain-load characteristics when the rubber is attached to the circumscribed circle of the steel cord, the additional load W at 0.35% elongation is 0.065% or less. ₁ (N) and additional load W at 0.45% elongation ₂ (N) is the following formula,
W ₂ -W ₁ <20 · S
Satisfied.

  According to the rubber-steel cord composite of the present invention, a plurality of the steel wire bodies wound on separate reels are bundled through a single base to form the steel cord, and the steel cord is a rubber cord. After being coated with, the steel cord is manufactured by being embedded in a rubber composite, or a plurality of the steel wire bodies wound on separate reels are bundled through a single slit to form the steel cord. On the other hand, after the rubber is pressure-bonded from above and below, the steel cord can be embedded in a rubber composite for production.

  According to the present invention, the above configuration realizes a spiral belt layer that can flexibly deform with low rigidity in a low strain region, while exhibiting high rigidity as steel in a high strain region above a certain input. As a result, it is possible to obtain a pneumatic radial tire for a motorcycle with improved turning maneuverability (cornering performance) without impairing tire performance such as straight running performance, high speed performance, ride comfort, uniformity, etc. Became possible.

Hereinafter, preferred embodiments of the present invention will be described in detail.
FIG. 1 shows a schematic cross-sectional view of an example of a pneumatic radial tire for a motorcycle according to the present invention. As shown in the figure, the tire of the present invention includes a tread portion 11, a pair of sidewall portions 12 disposed on the inner side in the tire radial direction from both edge portions thereof, and a bead portion 13 connected to the inner side in the tire radial direction. The carcass is composed of at least one layer of carcass ply in which these parts are reinforced between the bead cores 21 embedded in the bead part 13 and the cords forming 60 to 90 ° with respect to the tire equatorial plane are covered with rubber. The layer 22 and at least one spiral belt layer 23 spirally formed substantially parallel to the tire equatorial plane are provided on the outer side in the tire radial direction.

  The present invention is characterized in that a rubber-steel cord composite having low rise rigidity and exhibiting rigidity at a certain load or more is applied to the spiral belt layer 23. That is, the spiral belt layer 23 is composed of a rubber-steel cord composite formed by embedding a steel cord composed of a plurality of steel linear bodies in rubber, and the rubber-steel cord composite satisfies the following conditions. It is important to be satisfied.

In the rubber-steel cord composite according to the present invention, it is added to the steel section cross-sectional area S (mm ² ) in the strain-load characteristic in a state where the rubber adheres to the circumscribed circle of the steel cord. The elongation when the load W is changed from 1500 × S (N) to 1600 × S (N) is 0.070% or less, preferably 0.065% or less. Similarly, the steel cord In the strain-load characteristics with rubber adhering to the circumscribed circle, the additional load W ₁ (N) at the initial 0.35% elongation and the additional load W ₂ (N) at the 0.45% elongation It is important that the load difference W ₂ −W ₁ is less than 35 · S, preferably less than 20 · S. Thereby, the characteristics of the rubber-steel cord composite can be exhibited and various performances can be improved in the product tire. Here, the steel section cross-sectional area S (mm ² ) of the steel cord is S = Σs, _where s ₁ , s ₂ ... Sn (mm ² ) is the cross-sectional area of the n steel filaments constituting the steel cord. obtained as _n .

  As the rubber-steel cord composite having the above-described characteristics according to the present invention, a plurality of steel wire bodies 1 spirally formed at substantially the same pitch as shown in FIG. The steel cords that are bundled without being twisted together and embedded in rubber can be suitably used. Here, the steel linear body 1 constituting the steel cord in the present invention is a steel in which a plurality of steel filaments are twisted together even if the steel filament has a substantially circular cross section, depending on the required strength and rigidity. A strand may be sufficient and what combined these may be sufficient.

  In general, steel cords that are formed by twisting steel filaments or steel strands that are twisted together with steel filaments must be twisted in the initial stage when there is a gap between the filaments or strands when a tensile load is applied. It shows low rigidity like a spring, and when the load increases and these contact and disappear, there is a characteristic that the rigidity rapidly increases. However, as described above, when this is embedded in rubber and vulcanized, the rubber inside the cord hardly changes in volume, so even if there is a gap, it can no longer be twisted and shows high rigidity from the beginning, It does not show physical properties such as when there is no rubber and the rigidity changes greatly from the middle.

  Therefore, as described above, by not twisting the filaments or strands that have been molded, it is possible to escape to the outside of the cord without confining the rubber inside the cord. It becomes possible to maintain the initial elongation like a spring. On the other hand, unless the shaped filaments and strands are twisted together, the reinforcing material density in the cross section cannot be increased even at the limit of driving, and sufficient strength cannot be obtained. Therefore, the bundled filaments or strands are bundled at substantially the same pitch and in the same phase, and the bundled filaments or strands do not interfere with each other and can increase the density of the reinforcing material, thereby improving the strength. It becomes possible to do.

  Further, in this case, as shown in the drawing, it is preferable that circumscribed circles of the shaping spiral of any one of the steel wire bodies and at least one other steel wire body overlap each other. That is, by arranging the steel linear bodies constituting the steel cord in a state where the circumscribed circles of the respective molds overlap each other, a high rigidity strength at a high load can be obtained.

  Further, in the rubber-steel cord composite shown in the drawing, it is also preferable that the structure and the amount of molding of all the steel linear bodies constituting the steel cord are the same, so that the stress is evenly distributed to each steel linear body. As a result, strength efficiency can be improved.

Furthermore, in the present invention, when the circumscribed circle diameter of the shaping spiral of the steel wire body 1 shown in the figure is D and the outer diameter is d, the following formula:
D> 2.5d
Is preferably satisfied. By making the diameter D of the circumscribed circle of the steel wire body 1 larger than the diameter d of the steel wire body 1 by 2.5 times, the initial rigidity and the high rigidity portion that can be demonstrated at a certain input or more. The rigidity difference between the rubber and the steel cord composite can be further enhanced.

  As another example of the rubber-steel cord composite having the above-mentioned characteristics according to the present invention, two to five steel linear bodies are excessively typed and twisted, and orthogonal to the longitudinal direction of the cord. In the circumscribed circle in the cross section, a steel cord in which a central angle with respect to an arc between the steel wire bodies is 180 ° or more is embedded in rubber can be preferably exemplified. FIG. 3 shows an example of such a rubber-steel cord composite. That is, a rubber-steel cord composite having a large gap such that a central angle (gap angle) α with respect to the arc is 180 ° or more when the arc between the steel wire bodies 2 is defined as the gap. Also in this case, by keeping the rubber inside the cord and allowing it to escape to the outside of the cord, it is possible to maintain the initial elongation like a spring by molding as with the raw cord even after vulcanization.

In this case as well, when the circumscribed circle diameter of the steel cord is D and the outer diameter of the steel linear body constituting the steel cord is d,
D> 2.5d
It is preferable that the difference between the initial rigidity and the high rigidity portion exerted at a certain input or more can be increased, and the characteristics of the rubber-steel cord composite can be further enhanced. .

  As a method for stably and efficiently producing such a rubber-steel cord composite, for example, a plurality of the steel wire bodies wound on separate reels are bundled through a single base to form a steel cord. This steel cord is coated with rubber and then embedded in a rubber composite, or a plurality of steel wires wound on separate reels are bundled through one slit to form a steel cord. For example, a method in which a steel cord is embedded in a rubber composite after the rubber is pressure-bonded to the cord from above and below is useful.

  As long as the rubber-steel cord composite used in the present invention satisfies the above-mentioned conditions relating to the cord structure, other specific cord structures, the number and diameter of the steel linear bodies, and the specific structure The material of steel and rubber is not particularly limited.

  Further, in the tire of the present invention, if the rubber-steel cord composite satisfying the above-described characteristics is applied to the spiral belt layer of the tire, the other tire structure, the material of each component, etc. The present invention is not particularly limited, and thereby the desired effect of the present invention can be obtained.

Hereinafter, the present invention will be described in more detail with reference to examples.
Rubber-steel according to the conditions shown in Table 1 below, using steel linear bodies (filaments or strands (brass plating): Cu 63% by weight, Zn 37% by weight) molded at the molding amount and pitch shown in Table 1 below A code complex was prepared. As the coating rubber, natural rubber (NR) 100 parts by weight, carbon black (HAF) 55 parts by weight, zinc oxide (ZnO) 7 parts by weight, sulfur 5 parts by weight, Co salt (cobalt naphthenate) 0. A rubber composition consisting of 1 part by weight was used.

  Each rubber-steel cord composite obtained was driven into a pneumatic radial tire (MC tire) for motorcycles having a spiral belt structure shown in FIG. 1 (tyre size: 190 / 50ZR17 spiral belt layer of 40/50 mm). The vibration absorption and cornering properties were evaluated according to the following, and the results are also shown in Table 1 below.

<Vibration absorption, lightness, cornering>
The test tire is mounted on a 100cc sports type motorcycle with a rim size MT6.00x17 rim and air pressure of 250kPa, running on the test course, and absorbing vibration, lightness and turning during straight running The cornering property during running was evaluated by a 10-point method based on the feeling of a test driver. In any case, the score is 8 or more.

＊１）コードを構成するフィラメント間に隙間を有する構造。
＊２）スチールコードを構成する全スチールフィラメントの断面積ｓ₁、ｓ₂…ｓ_n（ｍｍ²）の総和（Ｓ＝Σｓ_n）である。
＊３）ゴム−スチールコード複合体に対する付加荷重Ｗを１５００×Ｓ（Ｎ）から１６００×Ｓ（Ｎ）まで変化させた際の伸び量。
＊４）Ｗ₁はゴム−スチールコード複合体が０．３５％伸びた時の付加荷重（Ｎ）であり、Ｗ₂は０．４５％伸びた時の付加荷重（Ｎ）である。

* 1) A structure having a gap between filaments constituting the cord.
* 2) is the sum of the cross-sectional area s ₁ for all steel filaments constituting the steel _{cord, s 2 ... s n (mm} 2) (S = Σs n).
* 3) Elongation amount when the additional load W on the rubber-steel cord composite is changed from 1500 × S (N) to 1600 × S (N).
* 4) W ₁ is an additional load (N) when the rubber-steel cord composite is expanded by 0.35%, and W ₂ is an additional load (N) when the rubber-steel cord composite is expanded by 0.45%.

  As can be seen from the results in Table 1 above, in the tire of the example using the rubber-steel cord composite satisfying the predetermined characteristics according to the present invention, the cornering property is improved without impairing vibration absorption and lightness. It was confirmed that it could be done.

1 is a schematic cross-sectional view showing a pneumatic radial tire for a motorcycle according to the present invention. It is sectional drawing which shows the code | cord | chord part which concerns on the suitable example of the rubber-steel cord composite_body | complex which concerns on this invention. It is sectional drawing which shows the cord part which concerns on the other suitable example of the rubber-steel cord composite_body | complex which concerns on this invention. 5 is a cross-sectional view showing a cord portion according to a rubber-steel cord composite of Comparative Example 1. FIG. 6 is a cross-sectional view showing a cord portion according to a rubber-steel cord composite of Comparative Example 2. FIG. 6 is a cross-sectional view showing a cord portion according to a rubber-steel cord composite of Comparative Example 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Steel linear body 11 Tread part 12 Side wall part 13 Bead part 21 Bead core 22 Carcass layer 23 Spiral belt layer

Claims (10)

A tread portion, a pair of sidewall portions disposed on the inner side in the tire radial direction from both edges of the tread portion, and a bead portion continuous on the inner side in the tire radial direction of the sidewall portion. A carcass layer comprising at least one carcass ply in which a cord forming 60 to 90 ° with respect to the tire equatorial plane and covered with rubber is reinforced between the bead cores embedded in the tire, and the tire radial direction of the carcass layer In a pneumatic radial tire for a motorcycle, comprising at least one spiral belt layer formed on the outside and spirally wound substantially parallel to the tire equator plane,
The spiral belt layer is composed of a rubber-steel cord composite in which a steel cord composed of a plurality of steel linear bodies is embedded in rubber;
The steel wire is a steel filament, a steel strand formed by twisting a plurality of steel filaments, or a combination thereof,
The steel cord is formed by bundling a plurality of the steel wire bodies spirally formed at substantially the same pitch without being twisted at substantially the same phase,
In the strain-load characteristics when rubber is attached to the circumscribed circle of the steel cord, when the steel section cross-sectional area of the steel cord is S (mm ² ), the additional load W is 1500 × S (N). The amount of elongation when changing to 1600 × S (N) is 0.070% or less, and the additional load W ₁ (N) at the time of 0.35% elongation and the additional load W at the time of 0.45% elongation. ₂ (N) is the following formula,
W ₂ −W ₁ <35 · S
A pneumatic radial tire for motorcycles that satisfies the requirements. Wherein with any one of the steel wire shaped body, and at least one other steel linear body according to claim 1 pneumatic radial tire for a motorcycle according to the circumscribed circle between the typed spiral overlap. The pneumatic radial tire for a motorcycle according to claim 1 or 2, wherein the structure and the amount of molding of the plurality of steel linear bodies are all the same. When the circumscribed circle diameter of the molding spiral of the steel linear body is D, and the outer diameter of the steel linear body is d, the following formula:
D> 2.5d
The pneumatic radial tire for a motorcycle according to any one of claims 1 to 3 , which satisfies the following conditions. A tread portion, a pair of sidewall portions disposed on the inner side in the tire radial direction from both edges of the tread portion, and a bead portion continuous on the inner side in the tire radial direction of the sidewall portion. A carcass layer comprising at least one carcass ply in which a cord forming 60 to 90 ° with respect to the tire equatorial plane and covered with rubber is reinforced between the bead cores embedded in the tire, and the tire radial direction of the carcass layer In a pneumatic radial tire for a motorcycle, comprising at least one spiral belt layer formed on the outside and spirally wound substantially parallel to the tire equator plane,
The spiral belt layer is composed of a rubber-steel cord composite in which a steel cord composed of a plurality of steel linear bodies is embedded in rubber ;
The steel wire is a steel filament, a steel strand formed by twisting a plurality of steel filaments, or a combination thereof,
In the circumscribed circle in the cross section orthogonal to the longitudinal direction of the steel cord, the steel cord is formed by twisting 2 to 5 of the steel wire bodies by excessively shaping them and twisting them together. The central angle with respect to the arc between the rods is 180 ° or more,
In the strain-load characteristics when rubber is attached to the circumscribed circle of the steel cord, when the steel section cross-sectional area of the steel cord is S (mm ² ), the additional load W is 1500 × S (N). The amount of elongation when changing to 1600 × S (N) is 0.070% or less, and the additional load W ₁ (N) at the time of 0.35% elongation and the additional load W at the time of 0.45% elongation. ₂ (N) is the following formula,
W ₂ −W ₁ <35 · S
A pneumatic radial tire for motorcycles that satisfies the requirements. When the circumscribed circle diameter of the steel cord is D and the outer diameter of the steel linear body constituting the steel cord is d, the following formula:
D> 2.5d
The pneumatic radial tire for a motorcycle according to claim 5, wherein: In the strain-load characteristics when rubber is attached to the circumscribed circle of the steel cord, the elongation amount when the additional load W is changed from 1500 × S (N) to 1600 × S (N) is 0.065. The pneumatic radial tire for a motorcycle according to any one of claims 1 to 6, wherein the pneumatic radial tire is a motorcycle. In the strain-load characteristics when rubber is attached to the circumscribed circle of the steel cord, an additional load W ₁ (N) at 0.35% elongation and an additional load W ₂ (N) at 0.45% elongation. And the following formula,
W ₂ −W ₁ <20 · S
The pneumatic radial tire for a motorcycle according to any one of claims 1 to 7, wherein: The rubber-steel cord composite is formed by bundling a plurality of the steel wire bodies wound on separate reels through one base to form the steel cord, and the steel cord is coated with rubber, and then rubber The pneumatic radial tire for a motorcycle according to any one of claims 1 to 8 , which is manufactured by being embedded in a composite. After the rubber-steel cord composite is bundled by passing a plurality of the steel wire bodies wound on separate reels through one slit to form the steel cord, and rubber is pressed against the steel cord from above and below. The pneumatic radial tire for a motorcycle according to any one of claims 1 to 9 , wherein the steel cord is embedded in a rubber composite.

Images